1. Field of the Invention
The present invention relates to a liquid crystal display device and method of driving thereof. In particular, the present invention relates to a driving circuit which drives a liquid crystal panel by using a dot inversion driving method, a display device having the driving circuit, and a method of driving a liquid crystal panel.
2. Description of the Related Art
In driving a liquid crystal panel, an A.C. driving method is employed in order to improve reliability. According to the A.C. driving method, polarity of voltage applied to a liquid crystal is inverted every frame. Such a polarity inversion driving method is employed in particular in a liquid crystal panel of an active matrix type, and includes a gate line inversion (COM inversion) driving method, a data line inversion driving method and a dot inversion driving method which can prevent the flicker from occurring. According to the gate line inversion driving method, the polarity of voltages applied to data signal lines is inverted every gate signal line. According to the data line inversion driving method, the polarity of voltages applied to the data signal lines is inverted every data signal line. According to the dot inversion driving method, the polarity of voltages applied to the data signal lines is inverted every pixel in a horizontal direction and in a vertical direction.
According to the gate line inversion driving method, the voltage Vcom of a common electrode (COM electrode, counter electrode) can be switched. As a result, it is possible to reduce voltage amplitude of a video voltage about as half as that in the case of the dot inversion driving method and thus to suppress power consumption. In this case, however, the same polarity appears in line with the horizontal direction and thus the flicker causing a horizontal line tends to occur when a driving frequency is decreased. On the other hand, according to the dot inversion driving method, the voltage Vcom of the common electrode is fixed and the polarity of the video voltage is switched between the positive polarity and the negative polarity for each pixel. As a result, the flickers accompanying the inversion driving are canceled each other out between all the adjacent pixels. Thus, the flickers can be most suppressed and the visually highest picture quality can be realized.
With regard to a driving circuit of a display panel, the following techniques are disclosed, in which a power recovery circuit for collecting a part of driving electric power of the display panel is provided for the purpose of reducing the electric power consumption.
Japanese Laid-Open Patent Application JP-P2000-181405A discloses a method of driving a plasma display panel (PDP) having a power recovery circuit which collects electric power of an address electrode by using an LC resonance circuit. In the plasma display panel according to conventional technique, power collection and power reuse related to charging of electrostatic capacitance accompanying the load for a driving power supply are performed through the resonance between the electrostatic capacitance and an inductance element. The power recovery circuit has n (n is not less than 2) inductance elements connected in series and m (m is not less than 1 and not more than n) switching elements which are connected in parallel to respective of m of the inductance elements. The inductance of the power recovery circuit is changed in accordance with increase and decrease of the load such that power collection efficiency is kept constant.
Japanese Laid-Open Patent Application JP-P2000-172231A discloses a data line driving circuit having a charge collecting circuit which collects charges of the data line by the use of an LC resonance circuit. The data line driving circuit of a matrix display has: a sample/hold circuit for sampling data; a read/write circuit for transmitting the sampling data to an output circuit; the output circuit connected to a power supply, and amplifying and transmitting the received data to a liquid crystal panel; and the charge collecting circuit. The charge collecting circuit collects panel charges by switching a connection of a column line. A power supply interconnection for the output circuit is used not only for the charge supplying but for the charge collection, and is connected to the power recovery circuit which switches between the power supply and a charge collection path.